Add programming language filtering to `/projects`

What does this MR do?

This merge request adds a query parameter to the /projects endpoint which allows a consumer to filter projects based on programming language used.

I'm looking for some more info/feedback regarding:

• Whether the URL parameter should be a (case insensitive?) string or an ID with a separate endpoint for getting programming language IDs.
• Whether a threshold for language percentage should be used or added to the query parameter.
• Whether I should mock DetectRepositoryLanguagesWorker (or if such a mock already exists).
• The efficiency of the SQL query.

Once these concerns are resolved, I'll do the changelog entry, update the docs, and remove the WIP label.

What are the relevant issue numbers?

Closes #51759 (closed).

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer